Recently, as application devices have increased in size and capacity, the demand for a power semiconductor device having a high breakdown voltage, a high current, and a high-speed switching characteristic has been on the rise.
The power semiconductor device requires low impedance and a low saturation voltage in order to allow a large amount of current to flow and reduce a loss of power while electricity is transmitted. Further, the power semiconductor device should be capable of resisting a backward high voltage of a PN junction applied to both ends of the power semiconductor device in an off-state or when a switch is turned off. That is, the power semiconductor device basically requires a high breakdown voltage.
In power semiconductor devices, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is the most typical field effect transistor in digital circuits and analog circuits.
When a power semiconductor device is manufactured, the required concentration and the thickness of an epitaxial region or a drift region of a raw material to be used depends on the rated voltage of the semiconductor device. In order to obtain concentration and thickness of a raw material required under a breakdown voltage theory and an appropriate breakdown voltage at a desired level, it is required to minimize an increase in a surface electric field at an interface of a semiconductor and a dielectric material by appropriately producing an electric field induced by a depletion layer in a reverse bias mode of a PN junction, appropriately using a PN junction structure, and to design a power semiconductor device to sufficiently resist even an inherent threshold electric field of the raw material in terms of breakdown of the power semiconductor device.
In particular, the state of a SiC interface and a silicon oxide film functioning as a gate insulation film in a MOSFET using a silicon carbide (SiC) is poor, and it influences flow of an electric current flowing through a channel created at sides of the silicon oxide film, so mobility of electrons is greatly decreased.
Further, the MOSFET of the related art enters a floating state in which an electrical signal cannot be directly supplied to a base region.
The Description of the Related Art is made to help understanding the background of the present disclosure, and may include matters out of the related art known to those skilled in the art.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.